1. Field of the Invention
The present invention relates to a device that assembles syringes for use in medical practice.
2. Description of Related Art
In recent years, syringes for injecting drug solutions have often been provided as prefilled syringes that are previously filled with drug solutions. An example of the configuration of a syringe formed with a barrel and a plunger is shown in FIGS. 10A, 10B, 11A, 11B and 12.
The barrel 101 is a cylindrical component formed of synthetic resin; at one end thereof, a luer taper portion for the attachment of an injection needle is formed. The luer taper portion is covered with a sealing member 102 that is formed of rubber or soft synthetic resin. A shoulder portion that is formed in the process of narrowing the barrel to the thickness of the luer taper portion in a downward direction is a taper portion 101a. A flange 103 is formed at the other end of the barrel 101. The flange 103 is designed for the attachment of a grip member (not shown) underneath which first and second fingers are put; the flange 103 is not circular and is shaped to have a major axis and a minor axis. In FIG. 11A, an example of the flange 103 that is rectangular with rounded corners is shown; however, the flange 103 may have another shape such as an oval shape.
A gasket 104 formed of rubber or soft synthetic resin is inserted into the barrel 101. In the end face of the gasket 104 opposite the end face pointing to the luer taper portion, a screw portion 105 is formed in a position that coincides with the central axis of the barrel 101. The screw portion 105 is a right-hand female screw.
A plunger rod 106 is combined with the gasket 104. The plunger rod 106 is a component that is cross-shaped in cross section and is formed of synthetic resin; at one end thereof, a knob 107 for putting thereon the thick of a thumb is formed. On the other end of the plunger rod 106, a screw portion 108 that is screwed into the screw portion 105 of the gasket 104 is formed in a position of the central axis. The screw portion 108 is a right-hand male screw. By tightly screwing the screw portion 108 into the screw portion 105 of the gasket 104 within the barrel 101, the gasket 104 and the plunger rod 106 are integrally coupled to constitute the plunger 109 (see FIG. 12), and the barrel 101 and the plunger 109 constitute a syringe 100.
An automated line is used to manufacture the syringes 100. In the automated line, an assembly device is included that performs an operation of screwing the plunger rod into the gasket within the barrel. Examples of this type of assembly device are disclosed in patent documents 1 and 2.
In the syringe assembly device disclosed in patent document 1, while a plunger rod is so supported at a given height that it cannot be rotated, a barrel is rotated, and thus the plunger rod is screwed. The barrel is rotated by a belt mechanism that is obliquely provided with respect to its cylindrical surface. While the barrels are transported by an arrangement disc (wheel), labels are attached on them.
In the syringe assembly device disclosed in patent document 2, while a plunger rod is supported with a slider moving up and down due to the shape of a three-dimensional cam such that the plunger rod cannot be rotated, a barrel is rotated to perform screwing of the plunger rod. The barrel is rotated by a belt.
Patent document 1: JP-A-2002-95746
Patent document 2: JP-A-2004-195556